Thermal insecticide fogger

ABSTRACT

A THERMAL FOGGER HAVING A MILTIPLE TANK. LIQUID PETROLEUM GAS FUEL SUPLY FEEDING THEOUGH LINE MEANS TO A COMMON BURNER OUTLET FOR COMBUSTION WITHIN A HEATER BODY, A SOURCE OF LIQUID INSECTICIDE INCLUDING LINES MEANS COMPRISED OF A SPRIAL VAPORIZER COIL LOCATED IN THE HEATER BODY AND A FOG OUTLET FROM WHICH THE INSECTICIDE IS DISCHARGED AS A FOG, WHERE THE HEATER BODY IS LOCATED NEXT TO THE FUEL TANKS AND IA HEAT CONDICTIVE TO RADIATE HEAT THEREAGAINST FOR STABLIZING DURING USE THE LIQUID FUEL TEMPERATURE AND THEREBY ITS PRESSURE, FUTHER WHERE THE FUEL COMBUSTION IN THE HEATER BODY OCCURES PRIMARILY AT THE FOG OUTLET END OF   THE HEATER BODY AND PEOPAGATES IN A COUNTERFLOW MANNER TO THE INSECTICIDE FLOW OVER VAPORIZER COIL TO DISCHARGE AS PRODUCTS OF COMBUSTION AT THE REMOTE END OF THE HEATER BODY FROM THE FOG OUTLET, AND WHERE PASSAGE MEANS CONNECT THE SEPARATE FUEL TANKS TO THE COMMON BURNER OUTLET AND INCLUDE CHECK MEANS FORMED AS PART OF EACH TANK OPENING PROBE SO THAT EITHER FUEL TANK CAN BE REMOVED FROM THE FOGGER WITHOUT LEAKAGE FROM THE OTHER TANK.

R. L. KONLE Nov. 30, 1971 Filed June 26, 1970 INVENTOE obc rf Z @l/di Nov. 30, 1971 K L 3,623,260

THERMAL INS ECTICIDE FOGGER Filed June 26, 1970 2 Shouts-Slm-ot 3 INVENTOE Qwe/z L Kcw/e ATT Y.

United States Patent Office 3,623,260 Patented Nov. 30 1971 3,623,260 THERMAL INSECTICIDE FOGGER Robert L. Konle, New Berlin, Wis., assignor to McGraw-Edison Company, Elgin, Ill. Filed June 26, 1970, Ser. No. 50,121 Int. Cl. A01rn 13/00, 19/00 US. Cl. 43-129 17 Claims ABSTRACT OF THE DISCLOSURE A thermal fogger having a multiple tank, liquid petroleum gas fuel supply feeding through line means to a common burner outlet for combustion within a heater body, a source of liquid insecticide including lines means comprised of a spiral vaporizer coil located in the heater body and a fog outlet from which the insecticide is discharged as a fog, where the heater body is located next to the fuel tanks and is heat conductive to radiate heat thereagainst for stabilizing during use the liquid fuel temperature and thereby its pressure, further where the fuel combustion in the heater body occurs primarily at the fog outlet end of the heater body and propagates as flame in a counterflow manner to the insecticide flow over the vaporizer coil to discharge as products of combustion at the remote end of the heater body from the fog outlet, and where passage means connect the separate fuel tanks to the common burner outlet and include check means formed as part of each tank opening probe so that either fuel tank can be removed from the fogger without leakage from the other tank.

Increased participation in outdoor activities and the wide variety of insecticides have increased the demand for a reliable but portable economical insecticide dispenser. It is possible to vaporize the normally liquid insecticide by heating it to within a specific temperature range so as to be discharged as fog. The advantages of insecticide fog over an insecticide spray or mist include the fact that it has more killing intensity over a wider area for the same volume of insecticide, it is thoroughly effective for killing insects in the presence of fog, and also it has minimal settling to leave less sometimes undesirable residue.

Devices for thermal fogging insecticides are known and frequently utilize an LPG or liquid petroleum gas, such as propane, as a burning fuel to heat the liquid insecticide in a vaporizer tube to be discharged then to the atmos phere as a fog. Propane, however, is quite difficult to confine and dispense since its pressure is very sensitive to temperature. For example, propane has a vaporizing pressure of approximately 125 p.s.i.g. at an ambient temperature of 70 F., whereas at 100 F., its vaporizing pressure increases to approximately 190 p.s.i.g., and at 130 F. the vaporizing pressure increased to approximately 285 p.s.i.g. Although it is possible to utilize some pressure lowering regulator between the liquid fuel and its discharge as a gas to the burner, this added space and weight requirements and cost of such equipment does not prove to be entirely satisfactory.

Another object of this invention is to provide a fuel vabilizing the fuel pressure is that fuel discharge from its high pressure liquid state to its natural vapor state absorbs by heat of vaporization tremendous quantities of heat from the fuel tank to reduce the fuel temperature and pressure. For a large output portable fogger where the fuel is discharged at a high rate, unless heat is added to the fuel tank the resulting fuel pressure drop can seriously impair the efiiciency of the unit if not totally render it inoperative.

Accordingly, an object of this invention is to provide a large output capacity portable thermal fogger that utilizes two or more interconnected conventional propane cylinders or tanks, each confining liquid fuel under the vaporizing pressure until being discharged as gas from a common burner outlet, and further where check means is provided in the probe that opens each fuel tank to the burner outlet such that any tank can be removed without bleeding the entire fuel system.

Another object of this invention is to provide a fuel vaporizing heater body having a heat conductive wall in closely spaced but facing adjacent relation to the sides of the propane fuel tanks such that heat is radiated against the tanks to help maintain them, even during discharge of the propane, at a more regulated temperature within limits for improved fuel tank pressure and burner control.

Another object of this invention is to provide a particular fuel vaporizing coil and enclosing heater body construction for improving the flame development and pro pagation over the coil within which the insecticide is vaporized such that vaporizer hot spots are eliminated or minimized, whereby combustion occurs oil? the burner tube near the fog outlet end of the heater body and the flame propagated back over the coil in a counterflow direction to the insecticide and is discharged from the heater body through openings disposed radially from the burner tube itself.

These and other objects of this invention will be more fully understood and appreciated after reviewing the following specification, the accompanying drawings forming a part thereof, wherein:

FIG. 1 is a side elevational view, partly broken away and in section, of a thermal fogger made according to the preferred teachings of this invention;

FIG. 2 is a sectional view, particularly as seen generally along line 22 in FIG. 1; and

FIGS. 3 and 4 are enlarged sectional views, as seen generally from lines 33 and 44 in FIG. 2, respectively.

Referring now to FIGS. 1 and 2, the illustrated unit 10 has a frame 12 of sheet metal or the like, which frame includes a carrying handle 14 since the unit is designed to be portable in use. A tank 16 is carried by the frame for holding liquid insecticide, and a small hand pump 18 when operated forces the insecticide from the tank through line 20, passage 22 in the mounting block 24, control valve 26, and line 27 including a part formed as a spiral vaporizer coil 28 to a discharge nozzle 30. A heater body 32 is disposed over the vaporizer coil 28 and completely encloses the coil.

The heater body 32 includes a circumferential wall 34 disposed in outwardly adjacent concentric relation to the coil 28, the outboard end wall 36 and inboard end wall 38 are connected across the circumferential wall at opposite ends of the coil to enclose the coil. A burner tube 40 extends snugly through an opening in the inboard end wall 38 and has a fuel outlet 39 connected by fuel line 41 to a source of combustible fuel. The fuel sources as proposed herein includes a pair of conventional propane tanks or cylinders 42 and 43 supported by a typical threaded neck 44 within a socket 46 in the mounting block 24. Pas sage means 48 in the mounting block connect the various sockets 47 to one another and with the line means 41 so that when the tanks are connected in the mounting block they communicate with one another and also through the fuel line 41 to the burner.

The fuel tanks or cylinders 42 and 43 are the type that confine a gas, such as propane, under sufficiently high pressure dependent on the temperature to maintain the fuel a liquid in the tank. The typical propane tank has a spring closed check valve 51 that maintains the tank closed except when the check valve is physically opened. To open the tank valve 51 automatically upon the tank being secured to its mounting block, there is typically provided a probe 52 as part of the mounting block that engages the stem 53 to unseat the valve and open the cylinder to the block passage. The subject probe 52 has a hollow bore 54 and an enlarged section 56 terminating at a small annular valve seat 58, where a check ball 60 cooperates with the seat to close the passage to atmosphere when the fuel tank is removed. A C-shaped roll pin 62 is in the enlarged bore 56 to hold the ball in the probe, and being hollow, does not block effective fuel flow past the opened check. This check means is in each probe and thereby automatically closes the mounting block passage to the atmosphere when a fuel tank is removed from the mounting block.

The fuel valve 50 upon being opened passes pressurized fuel through the fuel line to the outlet nozzle 39 of the burner tube 40. Immediately downstream, in the direction of the gas fuel discharge of the nozzle 39 there is provided opposed openings 66 for admitting air for admixture with the fuel gas Within the burner tube 40. An impingement pin 70 is typically located slightly in front of the direct line of the fuel nozzle 39 so that the fuel is directed against this pin and is forced to defer around its opposite sides. Preferably the pin is a hollow C-shaped roll pin with a lengthwise edge split open as at 71 opposite the nozzle 63. The ends of the pin are open also and extend through the tubular wall 72. of the burner tube and thereby admits ambient air within the circumferential wall but outside the heater body into heater body. Consequently, air can be drawn in through the pin side openings and discharged from the split for rapid and turbulent admixture with the fuel gas.

The burner tube outlet is located concentrically of the heat exchanger coil 28 and open for discharge in a direction towards the outboard end wall 36. By proper proportioning of the fuel nozzle 39, the air openings 66 and pin 70 size and location, it is possible to have the first flame develop off the burner tube 41 and only slightly spaced from the outboard end wall 36. Exhaust openings 74 are provided in the circumferential wall 34 of the heater body 30 adjacent the inboard end wall 38, radially spaced of the burner tube 41 and spaced axially from the last turn of the vaporizer tube. Consequently, the flame propagation is back over the coil in the direction from the outboard end wall toward the inboard end wall, and the products of combustion are discharged from the openings 72. This counterflow of insecticide through the vaporizer coil and flame propagation over the coil exposes the hottest part of the flame closely adjacent the discharge end of the coil 28 and the more cooled exhaust gases at the inlet end of the coil and eliminates or materially reduces hot spots of the vaporizer coil where carbon might build up. In actual use, the discharge temperature of the hot vaporous insecticide from nozzle 30 is hotter than the discharge temperature of the products of combustion from the exhaust openings 74.

Insulation 75 is provided on the inside of the outboard end wall 36 and on the inside of the circumferential wall to maintain the heater body safe to the touch of an operator. On the other hand, the inboard end wall 38 of the heater body is not insulated but is heat conductive to become hot during operation. The arrangement of the heater body relative to the fuel tanks is such that the inboard end wall 38 faces and is in somewhat closely spaced adjacent relation to the sides of the fuel tanks, effective thereby to radiate heat toward the fuel tanks. This is important since the discharge of the pressurized liquid fuel cools the fuel tank by approximately 185 B.t.u.s per pound of fuel discharge, which would otherwise significantly reduce the fuel pressure to a level that might even preclude operation of the burner. By this combustion will occur, the optimum performance of the thermal fogger can be achieved. This is particularly effective for initially igniting the burner and also for determining when the fuel tank might need to be replaced.

The multiple interconnected fuel tank arrangement disclosed herein is of extreme importance since it allows concurrent discharge from the separate fuel tanks While it also provides more tank surface area by which heat is absorbed from the ambient to reheat the fuel for stabilizing the pressure. Also, since any increase in pressure of the one tank over the other tank 'will automatically shut the check valve to the lower pressure tank, only the higher pressure tank will feed and thereby allow the lower pressure tank to become heated. Typically in fact since the discharging tank will drop in temperature to reduce its pressure, the tanks will alternately feed and become reheated under a hunting. modulating condition. Of even greater significance, however, the individual checks 60 permit the unrestricted removal of either fuel tank from the mounting block without accidental fuel leakage from the system.

What is claimed is:

1. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and spiral vaporizer coil between the insecticide tank and a discharge nozzle, a heater body having a circumferential wall in outwardly spaced adjacent concentric relationship to the coil and having opposing outboard and inboard walls connected across the circumferential wall at opposite ends of the coil and enclosing the coil, and the insecticide line means extending snugly through openings in each end wall and the discharge nozzle being adjacent the outboard end wall; means providing a heat source for the heater body including a burner tube disposed adjacent the inboard end wall, a fuel supply to a fuel outlet in the burner tube including a fuel tank mounting block and a pair of low pressure gas fuel tanks releasably connected to and supported from the block and means including a passage in the block connecting the tanks to each other and through a fuel line including a valve to the fuel outlet, and probe means in the mounting block for opening each respective fuel tank to the passage when the tank is secured to the block and check means in the mounting block as part of the probe means operable under superatmospheric pressure in the passage for closing same to the atmosphere when a respective tank is removed from the block; the circumferential Wall of the heater body having a plurality of exhaust openings located closely adjacent the inboard end wall and spaced radially of the burner tube, air inlet means to the burner tube located outside the heater body effective to admit air responsive to fuel discharge for admixture therewith into the heater body toward the outboard end wall centrally of the coil whereby combustion of the mixture occurs 011? the burner tube near the outboard end wall and spread as flame there from back over the vaporizer coil toward the inboard end wall and the products of combustion are discharged through said circumferential wall openings; and the heater body inboard end wall being in spaced but exposed facing proximity to the sides of the fuel tanks and being heat conductive operable to direct heat by radiation toward and against the fuel tanks.

2. A thermal fogger according to claim 1, wherein the heater body circumferential wall extends beyond the inboard end wall and terminates in closely adjacent spaced relation to the sides of the fuel tanks and further surrounds the air inlet means to the burner tube.

3. A thermal fogger according to claim 1, wherein the outboard end wall and circumferential wall of the heater body are insulated.

4. A thermal fogger according to claim 1, wherein the vaporizer has a uniform coil diameter for most of its axial length and is parallel to but inwardly spaced from the circumferential heater body wall, and wherein the exhaust openings on the circumferential wall are uniformly spaced around the wall at an axial location spaced from the vaporizer coil.

5. A thermal fogger according to claim 1, wherein the air inlet means include opposed openings in the burner tube at a location immediately downstream of the fuel outlet in the direction of fuel discharge, wherein the burner tube at a location immediately downstream of the air inlet means openings in the direction of fuel discharge includes a generally imperforate tubular wall concentrically aligned with the fuel outlet and the path of fuel discharge therefrom, and wherein a pin extends across the tubular wall in line with the fuel discharge and generally transverse to the opposed air inlet openings effective to divert the fuel dis charge and draw air in the openings by aspiration for common discharge from the burner tube.

6. A thermal fogger according to claim wherein the pin generally is C-shaped and hollow having a lengthwise slit open to the burner tube on the downstream side of the fuel outlet, and wherein the pin hollow is open through the tubular wall of the burner tube effective to draw outside air in and violently mix it with the discharged fuel within the burner tube.

7. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and vaporizer between the insecticide tank and a discharge nozzle, a heater body having a circumferential wall in outwardly spaced adjacent relationship to the vaporizer and having opposing outboard and inboard walls connected across the circumferential wall at opposite ends of the vaporizer and enclosing the same, and the discharge nozzle being adjacent the outboard end wall, means providing a heat source for the heater body including a burner tube disposed adjacent the inboard end wall, and a fuel supply to a fuel outlet in the burner tube including a fuel tank mounting block and a low pressure gas fuel tank releasably connected to and supported from the block and means including a passage in the block and a fuel line connecting the tank to the fuel outlet, probe means in the mounting block for opening the fuel tank to the passage when the tank is secured to the block, and air inlet means to the heater body effective to admit air responsive to fuel discharge for admixture therewith for combustion in the heater body and over the vaporizer, and the heater body inboard end wall being in spaced but exposed facing proximity to the side of the fuel tank and being heat conductive operable to direct heat by radiation toward and against the fuel tank.

8. A thermal fogger according to claim 7, wherein the heater body circumferential wall extends beyond the inboard end wall and terminates in closely adjacent spaced relation to the sides of the fuel tanks, and wherein the outboard end wall and circumferential wall of the heater body are insulated but the inboard end wall is heat conductive.

9. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and spiral vaporizer coil between the insecticide tank and a discharge nozzle, a heater body having a circumferential wall in outwardly spaced adjacent concentric relationship to the vaporizer coil and having opposing outboard and 'nboard walls connected across the circumferential wall ,at opposite ends of the vaporizer coil and enclosing the same, the discharge nozzle being adjacent the outboard end wall, means providing a heat source for the heater body including a burner tube disposed adjacent the inboard end wall and a fuel supply to a fuel outlet in the burner tube, the circumferential wall of the heater body having a plurality of exhaust openings located closely adjacent the inboard end wall and spaced radially of the burner tube, and air inlet means to the burner tube located outside the heater body effective to admit air responsive to fuel discharge for admixture therewith into the heater body toward the outboard end wall centrally of the coil whereby combustion of the mixture occurs off the burner tube near the outboard end wall and spreads as flame therefrom back over the vaporizer coil toward the inboard end wall and the products of combustion are discharged through said circumferential wall openings, and the heater body inboard end wall being in spaced but exposed facing proximity to the sides of the fuel tanks and being heat conductive operable to direct heat by radiation toward and against the fuel tanks.

10. A thermal fogger according to claim 9,, wherein the vaporizer has a uniform coil diameter for most of its axial length and is parallel to but inwardly spaced from the circumferential heater body wall, and wherein the exhaust openings on the circumferential wall are uniformly spaced around the wall at an axial location spaced from the vaporizer coil.

11. A thermal fogger according to claim 9, wherein the air inlet means include opposed openings in the burner tube at a location immediately downstream of the fuel outlet in the direction of fuel discharge, wherein the burner tube at a location immediately downstream of the air inlet means openings in the direction of fuel discharge includes a generally imperforate tubular wall concentrically aligned with the fuel outlet and the path of fuel discharge therefrom, and wherein a pin extends across the tubular wall in line with the fuel discharge and generally transverse to the opposed air inlet openings effective to divert the fuel discharge and draw air in the openings by aspiration for common discharge from the burner tube.

12. A thermal fogger according to claim 11, wherein the pin is generally C-shaped and hollow having a lengthwise slit open to the burner tube on the downstream side of the fuel outlet, and wherein the pin hollow is open through the tubular wall of the burner tube effective to draw air in from outside the heater body and discharge it within the burner tube for admixture with the fuel discharge.

13. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and vaporizer between the insecticide tank and a discharge nozzle, a heater body disposed in outwardly spaced adjacent relationship to the vaporizer and enclosing the same, means providing a heat source for the heater body including a burner tube and fuel supply means to a fuel outlet in the burner tube, said fuel supply means including a fuel tank mounting block and a pair of low pressure gas fuel tanks releasably connected to and supported from the block and means including a passage in the block connecting the tanks to each other and through a fuel line to the fuel outlet, and probe means in the mounting block for opening each respective fuel tank to the passage when the tank is secured to the block.

14. A thermal fogger according to claim 13, wherein check means is provided in the mounting block as part of each probe means operable under atmospheric pressure in the passage for closing the same to the atmosphere when a respective tank is removed from the block.

.15. A thermal fogger combination according to claim 13, wherein the heater body is in spaced but exposed facing proximity to the sides of the fuel tanks and is heat conductive at this location operable to direct heat by radiation toward and against the fuel tanks.

16. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and vaporizer coil between the insecticide tank and a discharge nozzle, a heater body in outwardly spaced adjacent relationship to the coil and enclosing the coil, and the insecticide line means extending snugly through openings in the heater body and the discharge nozzle being adjacent an outboard part thereof; means providing a heat source for the heater body including a burner tube disposed adjacent an inboard part thereof, a fuel supply to a fuel outlet in the burner tube including a fuel tank mounting block and a low pressure gas fuel tank releasably connected to and supported from the block and line means including a valve connecting the tank to the fuel outlet, and probe means in the mounting block for opening the fuel tank to the line means when the tank is secured to the block, the heater body having a plurality of exhaust openings located closely adjacent the inboard part thereof and spaced radially of the burner tube, air inlet means to the burner tube located outside the heater body effective to admit air responsive to fuel discharge for admixture therewith and common discharge into the heater body toward the outboard part thereof whereby combustion of the mixture occurs off the burner tube near the outboard part thereof and spreads as flame back over the vaporizer coil toward the inboard part thereof and the products of combustion are discharged through said exhaust openings; and the heater body having a part thereof in spaced but exposed facing proximity to the side of the fuel tank and being heat conductive at this part operable to direct heat by radiation toward and against the fuel tank.

17. A thermal fogger, comprising the combination of a tank for holding liquid insecticide, line means including a valve and vaporizer coil between the insecticide tank and a discharge nozzle, a heater body in outwardly spaced adjacent relationship to the coil and enclosing the coil, and the insecticide line means extending snugly through openings in the heater body and the discharge nozzle being adjacent an outboard part thereof; means providing a heat source for the heater body including a burner tube disposed adjacent an inboard part thereof,

a fuel supply to a fuel outlet in the burner tube includign a fuel tank mounting block and a pair of low pressure gas fuel tanks releasably connected to and supported from the block and line means including a valve connecting the tanks to each other and to the fuel outlet, and probe means in the mounting block for opening each respective fuel tank to the line means when the tank is secured to the block and check means in the mounting block as part of the probe means operable under superatmospheric pressure in the line means for closing same to the atmosphere when a respective tank is removed from the block; the heater body having a plurality of exhaust openings located closely adjacent the inboard part thereof and spaced radially of the burner tube, air inlet means to the burner tube located outside the heater body effectice to admit air responsive to fuel discharge for admixture therewith and common discharge into the heater body toward the outboard part thereof whereby combustion of the mixture occurs off the burner tube near the outboard part thereof and spreads as flame back over the vaporizer coil toward the inboard part thereof and the products of combustion are discharged through said exhaust openings; and the heater body having a part thereof in spaced but exposed facing proximity to the sides of the fuel tanks and being heat conductive at this part operable to direct heat by radiation toward and against the fuel tanks.

References Cited UNITED STATES PATENTS 3,134,191 5/1964 Davis 43129 3,214,860 11/1965 Johnson 43129 3,229,409 1/1966 Johnson 43129 ALDRICH 'F. MEDBERY, Primary Examiner US. Cl. X.R. 

